1. Field of the Invention
The present invention relates to an image stabilization apparatus that improves image blur caused by a camera shake, and also relates to an imaging apparatus or an optical apparatus that includes the image stabilization apparatus.
2. Description of the Related Art
Recent cameras can automatically perform essential image capturing processing (e.g., exposure determination and focus adjustment) in shooting operations to prevent even unskilled users from failing in shooting operations. An imaging system is configured to correct image blur that may be caused by a camera shake. Thus, there is almost nothing about the factors that may induce any errors in user's shooting operations.
An example system capable of correcting image blur caused by a camera shake is simply described below. The camera shake in a shooting operation is vibration in the frequency range from 1 Hz to 10 Hz. To capture an image free from image blur even when such a camera shake occurs when a shutter release button is pressed, it is necessary to detect a camera shake and move a lens to be used for image stabilization (hereinafter, referred to as “correction lens”) according to the detection value. Therefore, to capture an image free from image blur even when a camera shake occurs, it is necessary to accurately detect a camera shake (vibration) and correct a change of the optical axis caused by the camera shake.
Detection of the camera shake can be realized by a shake detection unit installed on a camera. In principle, the shake detection unit detects acceleration, angular acceleration, angular velocity, or angular displacement and performs processing for calculating an output for image stabilization (hereinafter, referred to as “image blur correction”). The camera system performs image blur correction based on the detected shake information to drive the correction lens that can move the photographic optical axis.
As discussed in Japanese Patent Application Laid-Open No. 2-162320 or in Japanese Patent Application Laid-Open No. 11-167074, a conventional camera shake correction apparatus uses a pair of lenses having opposite powers and balances these lenses.
However, according to Japanese Patent Application Laid-Open No. 2-162320, a link mechanism (a beam structure) extends in an optical axis direction to hold the lenses of opposite powers in a balanced state. Therefore, the body size of the camera shake correction apparatus is relatively large. As the correction lenses are supported by beam members rotatably around the beam members, camera shake correction may cause a positional deviation in the optical axis direction and may deteriorate the accuracy in the focus direction.
According to Japanese Patent Application Laid-Open No. 11-167074, two image blur correction apparatuses are prepared for correcting each image blur of two axes and therefore the apparatus body cannot be downsized.